I went out for coffee the other day with Susan Gluss, who has a job you would have to pay me a lot of money to do: Promote the Metropolitan Transportation Commissions 511 Rideshare program.

Lucky for her, shes got money to hand out right now in the form of free gas or groceries from Safeway. In three months of the program, theyve signed up 400 new carpoolers, each of whom is eligible to collect a maximum of $100 of these “Rideshare Rewards.

Susan is a lovely human being, and she seems to be doing a bang-up job, but its not easy to get people to share their cars with others, nor is it easy to find someone with a schedule that conforms to someone elses.

But its free money, so please, for Susans sake, give it a try.

I personally like the train. It takes 30-50 minutes longer than driving (except on Friday nights, when driving home to the Central Valley can easily take the same two hours, door-to-door, that transit and bicycling takes me), but you can seriously chill.

But if you can swing it, carpooling can give you the best of both worlds, and Susan knows this like circuit riders knew scripture.

“The average trip is 60 miles, roundtrip, she told me in one of several calls that culminated in our Starbucks rendezvous. “Assuming that theyre driving every other day, based on that and based on gas at $3 a gallon, we figure they can save $190 in gas alone.

Tell it, I say.

“And that doesnt include the wear-and-tear on the car, the reduced stress 

“Thats a sort of hidden surprise for people. They did not expect that, she says, breathlessly. “Getting to know their colleagues or their neighbors, making new friends, and discovering that its not such a bad thing to have company while youre inching forward in traffic. And better yet, scooting along in the carpool lane, bypassing the toll plaza on the Bay Bridge, all the while catching up on the latest neighborhood or office gossip.

The 511 Rideshare people estimate that their 400 new carpoolers are saving a total of $300 for the three months of the program, which is being extended through August and September in hopes of enticing another 100 carpoolers. That adds up to $116,000 in savings and 445,000 carpool miles and 29,000 fewer one-way vehicle trips. On Rideshares modest budget, its a lot more cost-effective than the $13.6 million Spare the Air free transit program, even if you assume some of the transit neophytes decide to park their cars for three months.

But 400 riders is a drop in the Bay when you consider 330,000 BART rides and 280,000 Bay Bridge crossings per day.

Spare the Air pulled in as many as 30,000 extra rides on BART and people noticed that the freeways werent as clogged as usual.

But the important thing that those 400 riders are doing is they are contributing to a larger effort that may, in time, actually stem the tide of increasing urban car use.

And in the process, theyre saving money and making friends, one of whom will certainly be Susan.